ctandc

I used to be a GM tech. I've been wrenching on cars / trucks for more than 25 years. Owned plenty of GM products, but I think this might be my last one.

In August '16 purchased a used 2011 Silverado 1500 4.8 2WD for my college aged son's primary vehicle. 60K miles. Very clean truck. Even though it was a 2WD a previous owner had installed a reputable aftermarket "leveling kit". This only consists of a metal spacer under the strut and and blocks in the rear lead springs. Larger tires / aftermarket wheels were installed. When I bought the truck, the TPMS light was constantly on and it appeared to be getting no signal from the TPMS system. Since I planned on installing new tires, I went ahead and ordered new AC Delco TPMS sensors for each wheel and had them installed when the new tires were put on. Turns out there were no TPMS sensors AT ALL before, as I suspected. I then programmed the TPMS system via the remote entry FOB and TPMS worked perfectly. No check engine lights.

Truck was driven daily for several weeks before the new tires and TPMS sensors were installed. A little while after tire / TPMS install my son reported the truck "acting weird". I scanned it, no outstanding codes and didn't think about it. A few days later it happened again and I witnessed it. While driving on the interstate, the Stabilatrak light lit up, then the DIC reported it was disabled and then reported Traction Control was disabled. When this happened, the speedometer dropped from 60mph to 0 mph and then bounced back and forth several times. Truck would stop doing it on it's own. When this happened, if traveling at low speeds, the transmission would shift extremely late and abrupt. Pulled the following codes from the truck:

P069E
P0700 - Transmission control system
U0073 - Control Module Communication Bus OFF
U0101 Lost Communication with TCM
U0109 Lost Communication with Fuel Pump control
U0100 Lost communication with ECM/PCM 'A'

Searched on Google, found a reference to a TSB and possible bad negative battery cable. Pressed for time (Son was going off to college - taking the truck - ironic it was bought so he'd have a reliable vehicle I didn't have to work on all the time) I installed a new GM Negative battery cable, cleaning all ground connections and making sure everything was connected good. Went ahead and replaced the battery since it was the original and 6 years old by the date code.

Son left for college. Problem still occurred and seem to occur more often. Searched some more and had the truck taken to a Chevrolet Dealer I've dealt with before and explained all the issues. They had the truck a full day and of course could not reproduce the problems. Recorded video of when it happened, showed them, they took it again and supposedly checked EVERYTHING listed on the GM TSB regarding electrical issues with these vehicles. They found that the wiring harness plug entering the EBCM (Electronic Brake Control Module - on the frame rail driver's side - the actual connector on the computer, one of the tabs that lock the harness in place was broken. They cable wrapped the connector, drove it several miles (at my request) and it seemed to be fine.

I bought a replacement, brand new GM ECBM ($180 my cost versus much higher through dealer) just in case. Issue started occurring again, and then a day or so later my son called me - the truck seemed completely dead (had power to all accessories) but would not even attempt to start. I drove to where the truck is to look at it. Battery was fine. I removed the cover from the underhood fuse box to check fuses / relays. Pulled the main start relay and was greeted with GREEN corrosion on the prongs on the relay. Pulled every relay / fuse, cleaned all contacts with sign of corrosion, used a bit of dielectric grease, truck started right up - drove with no errors.

Two days later, SAME symptom. No start. Took back to same dealer and showed them the corrosion on the fuse box. They replaced the entire fuse box (Comes with new relays).

So now I'm around $700 into this thing (out of warranty of course).

Symptoms came back a few days later. Son had to actually pull a main relay from the fuse box, reseat it and truck would start. Error lights and gauge cut out would happen randomly. Including lovely hard shifts (TCM not communicating).

I added a larger engine to chassis ground, ensuring all connections were solid. I also installed the ECBM I'd bought earlier. The existing part actually seemed to have burnt looking connections inside of it. Of course had to have the new ECBM programmed. The same Chevy dealer (today) had trouble getting it programmed. Had to talk to GM Tech Support / Engineering and were finally able to get it programmed. On the road leaving the dealership to go back to college, son called to let me know it was doing 'it" again. Gauges acting stupid, stabilatrak light etc.

I found a LONG thread here were several people had luck simply replacing the factory positive battery cable crimped on end. I will try that on both positive and negative cables and this weekend. At this point I'm ready to trade it in on something NOT GM.

tech2

when the fault it active you need to measure the CAN data bus voltages. These all can be measured at the dlc with a dvom. A full function scan tool will also be needed to see which modules are communicating and which are not.
It probably is not a vehicle battery power and grd issue but a module power and grd or com lines problem...hense the U codes. It not a chevy thing...all newer vehicles are using CAN communication.

no sense trying to test anything when the fault is not present as it will test normal. when this occurs post back.

ctandc

Thanks for the reply. Since the truck is my son's (bought it to replace an older vehicle so he'd have something more reliable - ironic) and he's at college, I'm only able to take my tools and go to the truck until Winter Break. So just to eliminate the easy / cheap stuff, I went ahead and replaced both battery terminal ends with high quality aftermarket parts. Truck started up fine. I had already cleared codes before I started (same codes I listed). After idling for a few minutes, the Stabiliatrak light came on / gauges wouldn't respond (tach was at 0 RPM) same old symptom. BUT when it happened, I could hear something under the hood 'engage' and when that happened that's when the truck threw codes. Cut the truck off, and it started up fine, no codes. Then a few minutes later, went to start it, would not turn over. Symptom we had before (and after a few times) since the unde rhood fuse box was replaced. Nothing I did would let the truck start - UNTIL I unseated the under hood fuse box, reseated it and the truck started right up. So I might be chasing two problems at this point. Just hoping the truck can get him through until Winter break. I'm working on sourcing a service wiring diagram and go from there.

FYI - Not sure it is related...but I mentioned replacing the ECBM (Electronic Brake Control Module) Apparently they had problems trying to get it programmed at the dealer. They had to call GM Tech Support / Engineering and they were able to get it programmed. Might not matter but in my searches I've seen errors in the data network cause difficulties when programming modules.

SIERRA_LC9

Did you find a fix for this issue?

My 2010 GMC Sierra 5.3 is throwing the same codes and going into limp mode with DTC's U0073, U0101, U0100, U0121,U0102, P0700, P069E.
Also, my truck has a small front leveling kit on the front, other than that she's stock. I live in Michigan (Salt State), but don't off road or anything.
I tried cleaning all grounds, just ordered new Pos & Neg Battery Cables.
Unplugged the TPA connector on the TCM, looked fine, undid the wiring by the trans to check for chaffed or pinched wire, nothing.
Unplugged ECM connector, applied Dielectric grease. Took the UBEC fuse block out, nothing odd. Swapped relays around.
Replaced the 120 Ohm resistor in the rear (twice), unplugged EBCM & FPCM connector with no abnormal corrosion found.
My truck will only act up above 60 Degrees, she was fine all winter.
Any help is much appreciated, I don't have the money to take her to a dealer, but at this point I just need it fixed.

BadchevyII

tech2

to diagnose communication codes
must know which modules the codes set in and which module has lost communication
ie the code is set in the bcm for lost communication with the abs module

Hot_Wire53

klimbik

I made a video to show all people how to relearn tpms sensors, so hopefully this will help enjoy!

mminor

Hi everybody, I have a 2011 Silverado LT with 111k miles purchased about 6 months ago from a local dealer. I recently started experiencing similar issues mentioned by OP and lately it has been getting worse. Today the door locks started going up and down for the first time. Previously I had only witnessed the traction/stabilitrack lighting up on the dash and gauges sweeping so I've decided to start researching on the forum vs taking the truck to a dealer.

I originally thought of a loose battery connection but that has not changed anything. I feel as though I'm heading down the same path as others with issues becoming progressively more problematic. Any update from the OP ctandc???

jorg_jorgenson

Hi All, i just joined this Forum so I could chime in on this issue.

I as well have a 2011 silverado 1500 5.3L with level kit.

It usually happens about once a month, for the past 8 months. I'd be driving my truck to or from work and all of the sudden my dash fan would quit working on my dash along with most of my dash lights. There would be an electronic 'clicking' coming from the passenger side door that I am positive is the sound of my window button being activated (because sometimes my window would start going down and I can not put it back up!). I would have to pull-over, turn the truck off, pull key out of ignition and basically try resetting the truck and then it would be fine and my window would work again.

Now for the past few weeks, this has been a much more frequent occurrence, and I am now experiencing the compass going in and out of service with the' clicking' of the passenger window (click once, I lose the compass, click again, compass direction shows up). My Stabilitrac light comes on, air bag service comes on, and sometimes my gauges zero-out like others have experienced.

Now the strange part... I found that if I am park and NOT on the brake, the clicking will be more like a buzz because it's doing it at such a high speed. as soon as I step ON the brake pedal, all of the clicking stops (although the window still does not operate and any dash lights that came on still stay on). I just wonder if this has something to do with the EBCM like others have noted above.

I'd hate for this issue to get worse to the point where I am unable to start my truck. I've also added some aftermarket HID lighting, light bar in grille, led interior lights etc. but I am starting to believe that none of these lighting upgrades are part of the larger problem...certainly annoying!